We turn now to a manhunt under way at this hour in arizona. Helicopters and horses in pursuit along a dangerous stretch of the mexican border. This morning, a shootout left one american border agent dead, another wounded. The asquloent died, 30-year-old nicholas ivy. Was this a mexican drug cartel in action? Cecilia vega joins us from the border. Reporter: Let me show you how close we're talking. That mountain right over my shoulder, that is the other side of the border. That is mexico. This area has earned the nickname cocaine alley. Today for the agents at this station, this is a place of mourning. It is remote, dangerous, and deadly. Here, early this morning on this dusty stretch of land where arizona meets mexico that three border patrol agents were fired on. One made it out safely. Another was shot twice and expected to recover. The third agent, 30-year-old nicholas ivy, was shot dead. We suspect this is probably some type of narcotics trafficking ent that these agents encountered but at this time, that would be speculative. Reporter: It was just before 2:00 in the morning when something triggered one of the many motion sensors on the border. Essential source automatically alert the nearest border patrol office. When they desect a certain weight, whether it's a smuggler, an illegal crosser, or a large animal, border patrol agents have to come out and investigate. The three agents headed 24r50e miles north of the border. As they headed up a hill, someone fired right at them in what is being described as an ambush. They work in the station name frd brian terry, the last agent killed on duty. His death attributed to a firearm sold in the fast and furious operation. It's unknown if the weapon that killed ivy has a link to that controversy. It's clear how dangerous life can be. Agent ivy died in the line of duty. Protecting our nation against those who threaten our way of life. His death strengthsens our resolve. Reporter: And this terrain out here, so rough that agents are still processing the crime scene. They say it could take a couple of days. The flags lowered today. Agents have been saying this has given them a resolve to make

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